Various forms of packaging machines are commercially available for the purpose of forming a vertical tube from a long strip of plastic film, paper or other flexible packaging material, for convenience herein referred to as "paper," and at the same time, introducing a product into the paper tube as it is formed, sealing it at its ends and cutting it to separate bag lengths. These prior devices are exemplified by U.S. Pat. Nos. 4,043,098, 4,136,505 and 4,171,605 which describe so-called "tubeless" form fill and seal machines characterized by having a very short fill tube from which back-up members or bars extend in a downward direction to provide a firm support for the operation of vacuum film advancing belt conveyors. U.S. Pat. No. 4,118,913 is similar except that the fill tube can be completely eliminated and the film advanced by means of vacuumized rolls which replace the belt conveyors. Another machine described in U.S. Pat. No. 4,291,520 includes a provision for stripping, clearing and flattening the end seal area of the paper tube.
These prior devices, while excellent for many applications, lack certain features required of the present invention. Machines of the general nature described in the patents are available commercially from Package Machinery Company of East Longmeadow, Mass. Thus, many basic machine elements used in the present invention, including the supporting framework, product distributor and funnel, vertical tube-forming guide and collar, film feeding conveyor, longitudinal seamer, sealing jaw and cut-off operating mechanism, as well as the timer and electric controller are commercially available and are well known to those skilled in the art. Accordingly, they need not be described in complete detail herein.
The deficiencies of the prior equipment in achieving the objectives of the present invention will now be described.
The product introduced into the tube of paper as it is being formed of course falls to the bottom of the freshly made bag. Accordingly, the location of the product in the bag cannot be precisely controlled. Thus, if the bag is pleated or gusseted, the product, normally a granular or particulate material, will be located on both sides of the gussets, i.e., between the gusset folds and each face. In addition, there is no way to keep the product centered in the bag intermediate the sealed ends. Instead, it is usually strung out between the top and bottom end seal. However, it is desirable for some applications to locate the product in a clump or mass about half way between the cut ends of the bag with one or both faces curved or blistered outwardly at that point to accommodate it. This may have application in a wide variety of applications such as product packed in a large display bag or for situations in which a bag is used at times to hold a smaller than normal product or quantity or, in the case of products that expand before they are removed from the bag. This would apply to expandable chemicals or foods which are hydrated and swell up while still in the bag or to popcorn that is intended to pop in the bag or even to bread and biscuit dough that is proofed or cooked in the bag. It can also be applied in packaging toys or hardware items that should be positioned precisely on center and at right angles to the ends of the bag. In the prior devices, products simply fall to the end of the bag and are located helter-skelter adjacent the bottom seal.
Another objective of the invention is to provide a means for forming deep gussets and especially an effective way to form a bag with gussets that have center creases or fold lines that touch each other or practically touch at the center of the bag and to bags in which one face of the bag is smaller in width than the other, e.g., a front face three inches wide and a back face five inches wide with gussets that touch at the center. As far as is known, there has been no provision for shaping bags produced on form, fill and seal machines in this way and at the same time, introducing product as desired into one side or both sides of the central gusset folds. When a belt or roller feed conveyor is used, it engages the sides of the tube from which bag lengths are cut and only one tube or compartment is present. An objective of the present invention is to form the flexible tube into two portions, one of which is preferably flat or collapsed and the other of which is expanded, then at the proper time, advance the tube by a conveyor means engaging only one of said two portions of the bag. For example, an optional conveyor is contemplated which may engage only the collapsed part of the bag and not the expanded portion.
Another problem with prior equipment is the lack of a provision for folding the filled bags transversely. The bag simply retains its pillow-shape after being severed from an adjacent bag. By contrast, it is an objective to fold one or both ends of the bag along transverse fold lines to bring the end seals to a position adjacent the center of the bag and to perform this operation automatically as the bags descend from the filling and sealing station.
Yet another problem with prior equipment is the lack of a provision for filling the bags with two different products simultaneously, particularly a liquid and a solid product. For example, in the case of foods and chemicals, it may be desirable to fill the tube with a liquid such as an oil and a solid such as a dry granular food, e.g., vegetable oil and unpopped popcorn. If liquid and solid materials were both introduced into the feed hopper above the fill tube, machine parts would become covered with oil creating an unsanitary condition by attracting dust. Moreover, the same quantity of oil might not be distributed to each successive bag.
These and other deficiencies of the prior art will be apparent from the following description setting forth certain illustrative embodiments of the invention by way of example.